There are various known tools and instruments for removing biological tissue samples from the body. For example, biopsy needles and punches are used when a small tissue specimen is required for examination, for example, to identify certain medical conditions. Another example of the biological tissue which is often desired to be removed or harvested is a hair follicle. Hair transplantation procedures are well-known, and typically involve harvesting donor hair grafts from the “donor areas,” for example, side and back fringe areas of the patient's scalp, and implanting them in a bald area (“recipient area”). Historically, the harvested hair grafts were relatively large (3-5 mm), although more recently the donor grafts may be single “follicular units,” which are naturally occurring aggregates of 1-3 (and much less commonly, 4-5) closely spaced hair follicles that are distributed randomly over the surface of the scalp. In one well-known process, a linear portion of the scalp is removed from a donor area by dissection, using a scalpel to cut down into the fatty subcutaneous tissue. The strip is then dissected (under a microscope) into the component follicular units, which are then implanted into a recipient area in respective puncture incisions made by a needle or razor blade. Forceps are typically used to grasp and place the follicular unit grafts into the needle puncture locations, although other instruments and methods are known for doing so.
In “Androgenetic Alopecia” (Springer 1996), M. Inaba & Y. Inaba disclose and describe a method for harvesting singular follicular units utilizing a hollow needle punch having a cutting edge and an interior lumen with a diameter of 1 mm, which is about equal to the diameter of critical anatomical parts of a follicular unit. The needle punch is axially aligned with an axis of a follicular unit to be extracted and then advanced into the scalp to cut the scalp about the circumference of the selected follicular unit. Thereafter, the follicular units are easily removed, e.g., using forceps, for subsequent implantation into a recipient site with a specially devised insertion needle.
U.S. Pat. No. 7,172,604 (Cole) discloses an instrument for the extraction of individual follicular units. Several steps in a process disclosed in Cole for extracting a hair follicle from the skin are shown in FIGS. 1A-1C. FIG. 1 shows a section of skin 20 containing a hair follicle 22 with a hair 24 disposed therein, wherein a tubular harvesting punch 26 contacts the surface of the skin. The punch 26 contacts the skin at an angle with respect to the skin's surface over the location at which the hair 24 emerges from the skin. A sharp end of the punch 26 penetrates the skin and advances to a depth D of between about 0.05-0.5 millimeters. The surgeon then angles the punch 26 to an angle along the same axis as the hair growth, and further advances the punch into the dermis to a second depth D2 of 2-7 millimeters.
Published U.S. Patent Application 20050267506 (Harris) discloses a method and apparatus for the extraction of follicular units by first scoring the outer skin layers with a sharp punch, removing the sharp punch, and then inserting a blunt punch into the incision to separate the hair follicular unit from the surrounding tissue and fatty layer to reduce the incidence of hair transection. Another U.S. Pat. No. 6,585,746 (Gildenberg) discloses a hair transplantation system utilizing a robotic system, including a robotic arm and a hair follicle end effector associated with the robotic arm that could be used to harvest hair follicles from the donor area.